The goals of the proposed investigation include the development and comparison of three scaling techniques capable of yielding equal sensory distances (equal loudness differences). These employ operant discrimination methodology with animal subjects. Our basic assumption is that if reinforcement schedule effects are parceled out, or held constant, total differences yielding similar levels of differential responding (behavioral equivalents) define equal sensory distances. We expect to compare families of behavioral equivalents obtained using the same tonal differences when various psychophysical methods are employed. For example, stimulus sets producing equivalent differential responding obtained using one technique will be compared with those obtained using another. The three experimental paradigms we plan to employ are: 1. Two-valued auditory intensity method (three-ply multiple schedule). 2. Tonal change-no-change method ("same" - "different" judgment). 3. Non-differential reinforcement of intensity pairs (differential responding attributable to stimulus intensity dynamism). Each method will be used to derive several values in order to determine internal consistency. In addition, the three methods will be compared to examine the generality of the findings. An appropritate transformation relating physical intensity to perceived loudness will be sought, consonant with the equal sensory distances derived from our three equal differential response techniques. It is also planned to make species comparisons between rats and chinchillas studied under comparable conditions.